A Streptomyces lusitanus DMZ-3 strain with potential to synthesize both insoluble and soluble melanins was detected. Melanins are quite distinguished based on their solubility for varied biotechnological applications. The present investigation reveals the enhanced production of insoluble and soluble melanins in tyrosine medium by a single culture. Streptomyces lusitanus DMZ-3 was characterized by 16S rRNA gene analysis. An enhanced production of 5.29 g/L insoluble melanin was achieved in a submerged bioprocess following response surface methodology. Combined interactive effect of temperature (50°C), pH (8.5), tyrosine (2.0 g/L), and beef extract (0.5 g/L) were found to be critical variables for enhanced production in central composite design analysis. An optimized indigenous slant culture system was an innovative approach for the successful production (264 mg/L) of pure soluble melanin from the droplets formed on the surface of the culture. Both insoluble and soluble melanins were confirmed and characterized by Chemical, reactions, UV, FTIR, and TLC analysis. First time, cytotoxic study of melanin using brine shrimps was reported. Maximum cytotoxic activity of soluble melanin was Lc50-0.40 µg/mL and insoluble melanin was Lc50-0.80 µg/mL.

Antibiotic-resistant bacteria causing foodborne serious illnesses can be found in contaminated food. Therefore, this study aimed to identify the pathogens, genes, and antimicrobial residues present in raw milk and meat. We collected 40 raw milk and 40 beef samples using the aseptic method from various parts of the Faisalabad metropolis, Pakistan. The samples were cultured on blood, MacConkey, and UTI chrome agar. The VITEK 2 compact system was used for microbial identification and determination of minimum inhibitory concentrations. Antimicrobial resistance genes for extended-spectrum β-lactamases, methicillin resistance in Staphylococcus aureus, and carbapenem resistance were identified using molecular techniques. ELISA was used to determine the tetracycline residue level in each sample. The beef samples showed polymicrobial contamination with 64 bacterial isolates, with Escherichia coli (29; 45.3%) and Klebsiella pneumoniae (11; 17.1%) predominating. The milk samples showed polymicrobial contamination with 73 bacterial isolates, with E. coli (22; 30%), K. pneumoniae (12; 16.4%), and S. aureus (10; 13.6%) forming the majority. Twenty-eight (43.7%) isolates from beef harbored tet genes, nineteen (29.6%) blaCTX-M, and fourteen (21.8%) blaNDM-1, and twenty-six (35.6%) isolates from milk harbored tet genes, nineteen (26%) blaTEM and blaCTX-M, and three (4%) blaNDM-1. Twenty-two (55%) each of the beef and milk samples exceeded the maximum residue limit for tetracycline. Polymicrobial contamination by bacteria possessing blaCTX-M, blaTEM, blaNDM-1, blaOXA, mecA, and tet genes was identified in food samples. The high tetracycline residue levels pose a serious health risk to consumers.

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Background Extensively drug-resistant (XDR) Salmonella enterica serovar Typhi (S. Typhi) poses a grave threat to public health due to increased mortality and morbidity caused by typhoid fever. Honey is a promising antibacterial agent, and we aimed to determine the antibacterial activity of honey against XDR S. Typhi. Methods We isolated 20 clinical isolates of XDR S. Typhi from pediatric septicemic patients and determined the minimum inhibitory concentrations (MICs) of different antibiotics against the pathogens using the VITEK 2 Compact system. Antimicrobial-resistant genes carried by the isolates were identified using PCR. The antibacterial efficacy of five Pakistani honeys was examined using agar well diffusion assay, and their MICs and minimum bactericidal concentrations (MBCs) were determined with the broth microdilution method. Results All 20 isolates were confirmed as S. Typhi. The antibiogram phenotype was confirmed as XDR S. Typhi with resistance to ampicillin (≥ 32 µg/mL), ciprofloxacin (≥ 4 µg/mL), and ceftriaxone (≥ 4 µg/mL) and sensitivity to azithromycin (≤ 16 µg/mL) and carbapenems (≤ 1 µg/mL). Molecular conformation revealed the presence of blaTM-1, Sul1, qnrS, gyrA, gyrB, and blaCTX-M-15 genes in all isolates. Among the five honeys, beri honey had the highest zone of inhibition of 7–15 mm and neem honey had a zone of inhibition of 7–12 mm. The MIC and MBC of beri honey against 3/20 (15%) XDR S. Typhi isolates were 3.125 and 6.25%, respectively, while the MIC and MBC of neem were 3.125 and 6.25%, respectively, against 3/20 (15%) isolates and 6.25 and 12.5%, respectively, against 7/20 (35%) isolates. Conclusion Indigenous honeys have an effective role in combating XDR S. Typhi. They are potential candidates for clinical trials as alternative therapeutic options against XDR S. Typhi isolates.

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